Bit Banger(s) we all have known.

[Tom Watson]

ard at p850ug1.demon.co.uk (Tony Duell) said:

> The earliest desktop comuter I know of with a bit-banged serial port is 
> the HP9830.
<<<deletia>>>
> I have never seen a bit-banged RS232 (or current loop) port on a 
> minicomputer. Anyone know of one?

Well (since you asked) the original serial interface for the HP 2116
computer (around 1966 or so) was a serial bit-banging interface.  You
needed to assemble the byte from the ASR-33 (or 35, take your pick)
teletype a bit at a time.  They later had the bit assembly/disassembly
register (this WAS pre UART chips) that did al the work.  Unfortunately
the "parallel" serial interface was only half duplex, as it used the
same register for both assembly and disassembly.  The "serial" (bit-
banging)  serial interface IIRC did not have this restriction.

Ah, history...



-- 
Tom Watson
tsw at johana.com


		
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